JSON.parse

The JSON.parse function is a method of the ECMAScript standard built-in object JSON, used to decode (parse) a JSON string. The FMZ Quant Trading Platform has extended it with an additional parameter safeStr on this basis.

    
    
    
JSON.parse(s)

    
    
    
JSON.parse(s, safeStr)

Examples

Decode (parse) a JSON string containing a large numeric value.

    javascript
    
    
function main() {
    let s1 = '{"num": 8754613216564987646512354656874651651358}'
    Log("JSON.parse:", JSON.parse(s1))          // JSON.parse: {"num":8.754613216564987e+39}
    Log("JSON.parse:", JSON.parse(s1, true))    // JSON.parse: {"num":"8754613216564987646512354656874651651358"}

    let s2 = '{"num": 123}'
    Log("JSON.parse:", JSON.parse(s2))          // JSON.parse: {"num":123}
    Log("JSON.parse:", JSON.parse(s2, true))    // JSON.parse: {"num":123}
}

    python
    
    
# You can use Python's third-party libraries to handle large numeric data.

    rust
    
    
fn main() {
    // Rust uses the JSONParse() function to parse JSON strings, without the safeStr parameter
    // Large numeric values that exceed the precision range will be parsed as f64, which may lose precision
    let s1 = r#"{"num": 8754613216564987646512354656874651651358}"#;
    Log!("JSONParse:", JSONParse(s1).unwrap()["num"].as_f64().unwrap_or(0.0));    // JSONParse: 8.754613216564987e39

    let s2 = r#"{"num": 123}"#;
    Log!("JSONParse:", JSONParse(s2).unwrap()["num"].as_f64().unwrap_or(0.0));    // JSONParse: 123
}

    c++
    
    
// Other solutions can be used to handle this.

Returns

Arguments

Remarks

The JSON.parse() function can correctly parse JSON strings containing large numeric values; when the safeStr parameter is set to a truthy value, large numeric values will be parsed as the string type.

The safeStr parameter position also supports passing in a reviver parameter, i.e. a function used to transform the result, which is called once for each member of the object; for specific usage, please refer to the relevant materials, which will not be elaborated here.

Only the JavaScript language is supported.

The safeStr parameter feature of the JSON.parse() function is not supported in the backtesting system.